1. Field of the Invention
The present invention relates to an automated placket shirt front forming machine and method for sewing placket shirts applicable to chain stitch, lock stitch and other types of sewing machines to provide a completely automatic apparatus and method which allows the machine operator to sew placket shirt fronts without having to master the art of sewing. More particularly, the present invention pertains to apparatus and method which requires the operator only to properly line up the placket shirt front, the placket and liner before activating the machine which then automatically completes all sewing, mitre and thread cutting and stacking of the finished placket shirt front.
The apparatus includes means for clamping and transferring the properly aligned parts to a means for sewing and slitting the placket shirt front, means for mitre cutting, thread cutting and stacking finished placket shirt fronts. The method of the invention includes the automatic sewing, mitring and stacking of placket shirt fronts by initiating the sewing of the placket shirt front, placket and liner intermediate the ends of the placket shirt front and sewing to one end of the placket shirt front.
The present method and apparatus of the invention provides for the automatic positioning of the material under the sewing machine and automatically sewing and incrementally advancing the placket shirt front maintained by the sew clamp through the sewing machine in coordination with the movement of the needle and slitting operation from a point intermediate the ends of the placket shirt front to one end of the placket shirt front. The invention provides an inexpensively formed placket shirt front that reduces labor and waste of placket shirt material components while increasing the precision and quality of the finished garment.
2. Description of the Prior Art
The prior art includes a variety of patents pertaining to semi-automatic sewing machines for sewing or providing assistance in the formation of garments such as placket shirt fronts. It is well recognized in the prior art and the placket shirt industry that the formation of placket shirt fronts involves considerable time, labor and skill of the placket sewing machine operator in not only positioning the placket shirt front, placket and liner but also in maintaining the position of the components during sewing so that the seams are straight and the placket shirt front when turned is not crooked, puckered or otherwise of an unacceptable quality. It is also recognized by those skilled in the art that formation of placket shirt fronts having buttoned fronts are generally even more difficult to produce as the tolerances in properly laying out and sewing the components of placket shirt are more demanding. For example, if stitching on either side of the placket or the slitting is not exact, the placket shirts formed may have a non-aligned front producing a "seconds" quality shirt. The skill of the sewing machine operator has heretofore been extremely important in lining up and sewing up the placket from the top or neck portion of the shirt down to the center or chest portion of the shirt. The traditional method of sewing placket and improvements in the prior art method of sewing placket shirts type shirts from the neck down has been the subject of various patents.
One such patent, Scott U.S. Pat. No. 3,871,307 pertains to a placket forming machine which employs a chain stitch sewing machine and provides a fabric workpiece clamp which is employed to clamp the garment and thereafter advance along a track at a regulated speed employing a hydraulic cylinder to advance the garment and clamp in the sewing operation. After completion of the sewing machine, a pair of knives are automatically engaged to pick up the stitch forming threads and to sever the threads. After the threads are severed, the clamp returns to the start position.
The operation of the chain stitch machine in Scott et al, U.S. Pat. No. 3,871,307 at best provides a semi-automated placket forming machine that requires considerable attention of the sewing machine operator and does not position, mitre, remove, or sew placket shirt fronts utilizing either the apparatus or method of the present invention to form the placket shirt front and also stack the finished product. In U.S. Pat. No. 3,871,307 the clamp assists the placket machine operator by guiding the aligned placket shirt parts through the machine. The apparatus and method disclosed in U.S. Pat. No. 3,871,307 is materially different than provided by the present invention since in the prior art patent the operator still begins sewing of the placket shirt and thereafter sews downward from the neck to the center of the shirt. Thereafter a chain stitch cutting apparatus engages the thread and cuts the thread so that the placket shirt front may thereafter be removed by the operator.
The operation of the placket shirt forming machine as described in U.S. Pat. No. 3,871,307 requires the operator to still operate the machine in coordination with the guidance of the placket clamp and necessitates the mitre cutting and stacking of the placket shirt front before beginning work on the formation of a second placket shirt which similarly requires the operator to line up the shirt front, placket and liner.
The present invention by way of contrast is not limited to any particular type of sewing machine and is completely automatic in that it only requires the operator to layer the garment materials. Once the materials are properly layered, the apparatus of the present invention automatically positions the garment under a sew clamp which then positions the garment under the sewing machine, sews, mitre cuts, cuts sewing threads and stacks the shirt front without further attention or skill of the operator. The fully automatic process of the invention is aided by a novel method in which the traditional method of sewing placket shirts starting from the neck of the shirt and sewing down to the center of the placket shirt is replaced by a method in which the placket shirt is sewn starting from the center portion of the shirt up to the neck or top of the shirt while the machine is slitting the liner, placket and shirt front. The method of the present invention allows the construction of a fully automated placket shirt forming machine that is not subject to the disadvantages and limitations in prior art placket sewing machines.
In Dorosz, U.S. Pat. No. 3,814,038 a sewing machine is provided having a pallet for supporting a workpiece for movement relative to the tool. The pallet is mounted on a moving means that is synchronized for movement with respect to the operation of the sewing machine needles. U.S. Pat. No. 3,814,038 does not pertain to placket forming machines. Dorosz does not suggest or contemplate the utilization of the present combination of elements and new and useful result provided by the transfer clamp, sew clamp and the mitring, cutting, and stacking operation of the finished product that is achieved by the present invention. Furthermore, the provision for the timed motion of the pallet utilizes apparatus that is entirely different from the present invention as the timed motion for the movement of the rack and pinion in relation to the penetration of the needle utilizes a nipple and eccentric cam arrangement.
The present invention unlike the prior art begins the sewing of the placket shirt front, placket and liner by initiating the slitting and sewing of the placket shirt front at a point at the lowest point of the placket shirt and thereafter sewing up to the top or neck position of the placket shirt thereby eliminating much of the labor, attention and skill heretofore required of sewing machine operators to not only increase productivity but also the accuracy and quality of the placket shirt fronts sewn in accordance with the method and apparatus of the present invention.
As a result of the method and apparatus the present invention provides an enormous economic advantage in the production of high quality placket shirt fronts without having to rely upon the skill of the placket sewing machine operator. One of the distinguishing features of the present invention is the utilization of a transfer clamp and sew clamp to increase productivity and to initiate the sewing operation of the placket shirt from the center or mid portion of the placket to the top or the neck portion of the shirt to provide a method and apparatus for increasing not only productivity and accuracy of the placket sewn shirt but also assist in the cutting, mitring and removal of the placket shirt front and the subsequent stacking of the finished placket shirt fronts.